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px4-firmware/nuttx/fs/nxffs/nxffs_inode.c

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/****************************************************************************
* fs/nxffs/nxffs_inode.c
*
* Copyright (C) 2011 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* References: Linux/Documentation/filesystems/romfs.txt
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <string.h>
#include <crc32.h>
#include <assert.h>
#include <errno.h>
#include <debug.h>
#include <nuttx/kmalloc.h>
#include <nuttx/mtd.h>
#include "nxffs.h"
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/****************************************************************************
* Public Types
****************************************************************************/
/****************************************************************************
* Public Variables
****************************************************************************/
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: nxffs_rdentry
*
* Description:
* Read the inode entry at this offset. Called only from nxffs_nextentry().
*
* Input Parameters:
* volume - Describes the current volume.
* offset - The byte offset from the beginning of FLASH where the inode
* header is expected.
* entry - A memory location to return the expanded inode header
* information.
*
* Returned Value:
* Zero on success. Otherwise, a negated errno value is returned
* indicating the nature of the failure.
*
* On return, the
*
****************************************************************************/
static int nxffs_rdentry(FAR struct nxffs_volume_s *volume, off_t offset,
FAR struct nxffs_entry_s *entry)
{
struct nxffs_inode_s inode;
uint32_t ecrc;
uint32_t crc;
uint8_t state;
int namlen;
int ret;
DEBUGASSERT(volume && entry);
memset(entry, 0, sizeof(struct nxffs_entry_s));
/* Read the header at the FLASH offset */
nxffs_ioseek(volume, offset);
memcpy(&inode, &volume->cache[volume->iooffset], SIZEOF_NXFFS_INODE_HDR);
/* Check if the file state is recognized. */
state = inode.state;
if (state != INODE_STATE_FILE && state != INODE_STATE_DELETED)
{
/* This can't be a valid inode.. don't bother with the rest */
ret = -ENOENT;
goto errout_no_offset;
}
/* Copy the packed header into the user-friendly buffer */
entry->hoffset = offset;
entry->noffset = nxffs_rdle32(inode.noffs);
entry->doffset = nxffs_rdle32(inode.doffs);
entry->utc = nxffs_rdle32(inode.utc);
entry->datlen = nxffs_rdle32(inode.datlen);
/* Modify the packed header and perform the (partial) CRC calculation */
ecrc = nxffs_rdle32(inode.crc);
inode.state = CONFIG_NXFFS_ERASEDSTATE;
memset(inode.crc, 0, 4);
crc = crc32((FAR const uint8_t *)&inode, SIZEOF_NXFFS_INODE_HDR);
/* Allocate memory to hold the variable-length file name */
namlen = inode.namlen;
entry->name = (FAR char *)kmalloc(namlen + 1);
if (!entry->name)
{
fdbg("Failed to allocate name, namlen: %d\n", namlen);
ret = -ENOMEM;
goto errout_no_offset;
}
/* Seek to the expected location of the name in FLASH */
nxffs_ioseek(volume, entry->noffset);
/* Make sure that the block is in memory (the name may not be in the
* same block as the inode header.
*/
ret = nxffs_rdcache(volume, volume->ioblock);
if (ret < 0)
{
fdbg("nxffsx_rdcache failed: %d\n", -ret);
goto errout_with_name;
}
/* Read the file name from the expected offset in FLASH */
memcpy(entry->name, &volume->cache[volume->iooffset], namlen);
entry->name[namlen] = '\0';
/* Finish the CRC calculation and verify the entry */
crc = crc32part((FAR const uint8_t *)entry->name, namlen, crc);
if (crc != ecrc)
{
fdbg("CRC entry: %08x CRC calculated: %08x\n", ecrc, crc);
ret = -EIO;
goto errout_with_name;
}
/* We have a good inode header.. but it still could a deleted file.
* Check the file state.
*/
if (state != INODE_STATE_FILE)
{
/* It is a deleted file. But still, the data offset and the
* start size are good so we can use this information to advance
* further in FLASH memory and reduce the search time.
*/
offset = nxffs_inodeend(volume, entry);
nxffs_freeentry(entry);
ret = -ENOENT;
goto errout;
}
/* Everything is good.. leave the offset pointing to the valid inode
* header.
*/
return OK;
/* On errors where we are suspicious of the validity of the inode header,
* we need to increment the file position to just after the "good" magic
* word.
*/
errout_with_name:
nxffs_freeentry(entry);
errout_no_offset:
offset += NXFFS_MAGICSIZE;
errout:
nxffs_ioseek(volume, offset);
return ret;
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: nxffs_freeentry
*
* Description:
* The inode values returned by nxffs_nextentry() include allocated memory
* (specifically, the file name string). This function should be called
* to dispose of that memory when the inode entry is no longer needed.
*
* Note that the nxffs_entry_s containing structure is not freed. The
* caller may call kfree upon return of this function if necessary to
* free the entry container.
*
* Input parameters:
* entry - The entry to be freed.
*
* Returned Value:
* None
*
****************************************************************************/
void nxffs_freeentry(FAR struct nxffs_entry_s *entry)
{
if (entry->name)
{
kfree(entry->name);
entry->name = NULL;
}
}
/****************************************************************************
* Name: nxffs_nextentry
*
* Description:
* Search for the next valid inode starting at the provided FLASH offset.
*
* Input Parameters:
* volume - Describes the NXFFS volume.
* offset - The FLASH memory offset to begin searching.
* entry - A pointer to memory provided by the caller in which to return
* the inode description.
*
* Returned Value:
* Zero is returned on success. Otherwise, a negated errno is returned
* that indicates the nature of the failure.
*
****************************************************************************/
int nxffs_nextentry(FAR struct nxffs_volume_s *volume, off_t offset,
FAR struct nxffs_entry_s *entry)
{
int nmagic;
int ch;
int nerased;
int ret;
/* Seek to the first FLASH offset provided by the caller. */
nxffs_ioseek(volume, offset);
/* Then begin searching */
nerased = 0;
nmagic = 0;
for (;;)
{
/* Read the next character */
ch = nxffs_getc(volume, SIZEOF_NXFFS_INODE_HDR - nmagic);
if (ch < 0)
{
fvdbg("nxffs_getc failed: %d\n", -ch);
return ch;
}
/* Check for another erased byte */
else if (ch == CONFIG_NXFFS_ERASEDSTATE)
{
/* If we have encountered NXFFS_NERASED number of consecutive
* erased bytes, then presume we have reached the end of valid
* data.
*/
if (++nerased >= NXFFS_NERASED)
{
fvdbg("No entry found\n");
return -ENOENT;
}
}
else
{
nerased = 0;
/* Check for the magic sequence indicating the start of an NXFFS
* inode. There is the possibility of this magic sequnce occurring
* in FLASH data. However, the header CRC should distinguish
* between real NXFFS inode headers and such false alarms.
*/
if (ch != g_inodemagic[nmagic])
{
/* Ooops... this is the not the right character for the magic
* Sequence. Check if we need to restart or to cancel the sequence:
*/
if (ch == g_inodemagic[0])
{
nmagic = 1;
}
else
{
nmagic = 0;
}
}
else if (nmagic < NXFFS_MAGICSIZE - 1)
{
/* We have one more character in the magic sequence */
nmagic++;
}
/* We have found the magic sequence in the FLASH data that may
* indicate the beginning of an NXFFS inode.
*/
else
{
/* The the FLASH offset where we found the matching magic number */
offset = nxffs_iotell(volume) - NXFFS_MAGICSIZE;
/* Try to extract the inode header from that position */
ret = nxffs_rdentry(volume, offset, entry);
if (ret == OK)
{
fvdbg("Found a valid fileheader, offset: %d\n", offset);
return OK;
}
/* False alarm.. keep looking */
nmagic = 0;
}
}
}
/* We won't get here, but to keep some compilers happy: */
return -ENOENT;
}
/****************************************************************************
* Name: nxffs_findinode
*
* Description:
* Search for an inode with the provided name starting with the first
* valid inode and proceeding to the end FLASH or until the matching
* inode is found.
*
* Input Parameters:
* volume - Describes the NXFFS volume
* name - The name of the inode to find
* entry - The location to return information about the inode.
*
* Returned Value:
* Zero is returned on success. Otherwise, a negated errno is returned
* that indicates the nature of the failure.
*
****************************************************************************/
int nxffs_findinode(FAR struct nxffs_volume_s *volume, FAR const char *name,
FAR struct nxffs_entry_s *entry)
{
off_t offset;
int ret;
/* Start with the first valid inode that was discovered when the volume
* was created (or modified after the last file system re-packing).
*/
offset = volume->inoffset;
/* Loop, checking each NXFFS inode until either: (1) we find the NXFFS inode
* with the matching name, or (2) we reach the end of data written on the
* media.
*/
for (;;)
{
/* Get the next, valid NXFFS inode entry */
ret = nxffs_nextentry(volume, offset, entry);
if (ret < 0)
{
fvdbg("No inode found: %d\n", -ret);
return ret;
}
/* Is this the NXFFS inode we are looking for? */
else if (strcmp(name, entry->name) == 0)
{
/* Yes, return success with the entry data in 'entry' */
return OK;
}
/* Discard this entry and try the next one. Here we set the
* next offset using the raw data length as the offset
* increment. This is, of course, not accurate because it
* does not account for the data headers that enclose the
* data. But it is guaranteed to be less than or equal to
* the correct offset and, hence, better then searching
* byte-for-byte.
*/
offset = nxffs_inodeend(volume, entry);
nxffs_freeentry(entry);
}
/* We won't get here, but for some compilers: */
return -ENOENT;
}
/****************************************************************************
* Name: nxffs_inodeend
*
* Description:
* Return an *approximiate* FLASH offset to end of the inode data. The
* returned value is guaranteed to be be less then or equal to the offset
* of the thing-of-interest in FLASH. Parsing for interesting things
* can begin at that point.
*
* Assumption: The inode header has been verified by the caller and is
* known to contain valid data.
*
* Input Parameters:
* volume - Describes the NXFFS volume
* entry - Describes the inode.
*
* Returned Value:
* A FLASH offset to the (approximate) end of the inode data. No errors
* are detected.
*
****************************************************************************/
off_t nxffs_inodeend(FAR struct nxffs_volume_s *volume,
FAR struct nxffs_entry_s *entry)
{
/* A zero length file will have no data blocks */
if (entry->doffset)
{
/* This is the maximum size of one data block. It is the physcal size
* of the block minus the minimum number of headers: block sna data
*/
uint16_t maxsize = volume->geo.blocksize - SIZEOF_NXFFS_BLOCK_HDR - SIZEOF_NXFFS_DATA_HDR;
/* This is the minimum number of blocks require to span all of the
* inode data. One additional block could possibly be required -- we
* could make this accurate by looking at the size of the first, perhaps
* partial, data block.
*/
off_t minblocks = (entry->datlen + maxsize - 1) / maxsize;
/* And this is our best, simple guess at the end of the inode data */
return entry->doffset + entry->datlen + minblocks * SIZEOF_NXFFS_DATA_HDR;
}
/* Otherwise, return an offset that accounts only for the inode header and
* the inode name.
*/
/* All valid inodes will have a name associated with them */
DEBUGASSERT(entry->noffset);
return entry->noffset + strlen(entry->name);
}
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